It was naivety on Sony's part. They knew PSP had a problem with ports, and tried to remedy it by making Vita's hardware something that could handle 3D console games with ease. They also tried avoiding the "PlayStation Portable" moniker by encouraging original titles over ports, in a move seemingly aimed at western studios. What they seemed to neglect was the fact that third party western developers have never really given a shit about handhelds and all they were going to get were ports, and C-team spinoffs from them no matter what.
I agree with you, no matter how much the internet community bitches and whines ports are an important part of a new system's library. Sometimes they help plant the seeds for future original entries in series, but most importantly they are the cheapest and easiest way to ensure a platform doesn't go weeks on end without a new release. The days where nothing comes out for Vita are its worse weeks even if Media Create/NPD/Chart-Track don't say as much. They're the image breakers.
Part of me wonders how much HD Collections have also hurt Vita since handheld ports used to sometimes be the only way old games see the light of day again. Are people really going to buy MGS2/MGS3 on a handheld six months after they rebought it for PS3? Probably not. Imagine how much healthier this thing would be if it got ports of Resident Evil 4, Yakuza 1&2, Kingdom Hearts, and more instead of those going to PS3. Shit, this thing's best seller in Japan is an expanded Persona 4 port, and I guarantee it wouldn't have sold nearly as well on Vita if there was a PS3 counterpart. The worst part is ... Sony popularized the HD Collection and the big Square Enix support is a near vaporware FFX port which would on its own probably would be a big seller, except for the fact it's also coming to PS3.
